The invention concerns a sealing system between two facing and mutually moving components for sealing a high-pressure side with respect to a low-pressure side. An outer component as an annular groove which opens towards the inner component and faces the low pressure side for acceptance of a sealing configuration as well as a second annular groove which opens towards the inner component and faces the high pressure side for acceptance of a pressure relief element. The sealing configuration includes a first sealing ring made from an elastically deformable material and a first preloading ring made from an elastic deformable material. The first sealing ring seats on the inner component and is tensioned in a radial direction by the first preloading ring, which also seals the first annular groove.
During operation of such sealing systems, i.e. during relative translational motion between the two components, a medium pressure increase in the intermediate spaces between the individual annular grooves and the elements provided therein can occur. This can be caused by disadvantageous velocity conditions associated with one component, for example a piston rod or a piston, in the associated installation space. In the event of disadvantageous velocity conditions between the seal and the opposing running surface, the hydrodynamic return transport properties of the seal can be insufficient to transport the resulting lubricant volume of the extending stroke back into the associated intermediate space. As a result of the accumulation of residual lubricant oil, a pressure increase can occur in the intermediate space, which can be multiples of the actual operating pressure. Such an increase in pressure can lead to damage or even rupturing of those components, thereby resulting in a breakdown in the entire system.
EP 0 946 837 discloses a pressure relief element which includes a sealing ring seating on an inner component and made from an elastically deformable material as well as a tensioning ring which radially surrounds the sealing ring, seals relative to the second annular groove, and is made from an elastically deformable material. A connecting channel in the sealing ring by means of which the high-pressure side and the low-pressure side can be connected to each other characterizes the pressure relief element. The connecting channel is closed by the sealing ring, which seals the high-pressure side relative to the low-pressure side and is opened when the pressure situation is inverted. A pressure relief element of this kind used in the above described sealing system serves as a kind of check valve which is opened as soon as the pressure PZ in the intermediate space between the sealing configuration and the pressure relief element exceeds a pressure PH on the high pressure side, Pz>PH. Through the opening of the connecting channel, the pressure in intermediate space can escape to the high pressure side. After relief, the pressure in the intermediate space is the same as that at the high-pressure side, PZ=PH.
It is the underlying purpose of the present invention to control the pressure relief of a sealing configuration within a sealing system in dependence on use such that pressure relief can first occur when the intermediate pressure is substantially larger than the high pressure, which is to be sealed.